The purpose of this project is to study the recipient response to corneal homografts relined with heterologous corneal endothelium. The project uses the feline model of keratoplasty and investigates immune mediated phenomena in the local area of the transplant (aqueous humor of anterior chamber) as well as systemically. The experimental approach is to: (1) establish normal immune status values in the model, (2) thoroughly characterize the recipient immune system following successful corneal homotransplantation and following induced transplant rejection, and (3) then compare the recipient response to heterologous corneal endothelial cell lined homografts. Correlated methods of analysis include (1) clinical measurements (slit lamp biomicroscopy, specular corneal endothelial cell microscopy, and pachometry), (2) morphological studies (scanning and transmission electron microscopy, aqueous cell cytology), and (3) immunological studies (immunoglobulin concentrations, specific antibody titers to transplant related- and unrelated antigens, lymphocyte blastogenesis, cell mediated cytotoxicity, and antibody cell mediated cytotoxicity). Further studies include: (1) the role of corneal endothelium in evoking suppressor-like activity following successful corneal transplantation, (2) the value of mixed lymphocyte response studies in predicting the successful outcome of impending corneal transplantation, and (3) the practical use of other heterologous replacement endothelial cells in corneal transplantation.